1. Field of the Invention
The present invention relates to a resin-type light guide plate composition, a backlight unit including the light guide plate formed using the composition, and a liquid crystal display including the backlight unit. More particularly, the present invention relates to a resin-type light guide plate composition, which can fabricate a light guide plate useful for a module-type backlight unit exhibiting excellent adhesion to a base film and enabling local dimming while having a low shrinkage rate, by a simple curing process and can form a thick film, a backlight unit including the light guide plate formed using the composition, and a liquid crystal display including the backlight unit.
2. Description of the Related Art
Liquid crystal displays are used in a wide range of applications, including notebook type computer, monitors, televisions, or outdoor electronic displays, because they have various advantages of a slim size, a lightweight design, low electric power consumption, and so on.
The liquid crystal display includes a liquid crystal panel and a backlight unit. The backlight unit supplies the liquid crystal panel with light, which is transmitted through the liquid crystal panel. Here, the liquid crystal panel adjusts the transmittance of light to display an image. Backlight units are classified into edge-type backlight units and direct-type backlight units depending on the arrangement of light sources.
In an edge-type backlight unit, a light source is arranged at either lateral side of a liquid crystal panel and a light guide plate is arranged in rear of the liquid crystal panel, so that light incident from the lateral side of the liquid crystal panel is guided to the rear side of the liquid crystal panel.
In a direct-type backlight unit, a plurality of light sources are provided on a rear surface of the liquid crystal panel, and light emitted from the plurality of light sources is directly supplied to the rear surface of the liquid crystal panel.
Examples of light sources for LCD include electroluminescence (EL) lamps, cold cathode fluorescent lamps (CCFLs), hot cathode fluorescent lamp (HCFLs), and light-emitting diodes (LEDs). Among the light sources, the LEDs are increasingly used owing to their advantages including low power consumption and high emission efficiency.
FIG. 1 is a schematic configuration view that illustrates an edge-type LED backlight unit.
In a case of an edge-type LED backlight unit, a plurality of LEDs 30 are mounted on a printed circuit board 10 and fixed on a lateral side of a light guide plate 40-A. The light guide plate 40-A allows light that is incident from the plurality of LEDs 30 to be evenly spread over a wide area of the light guide plate 40-A due to total reflection occurring a repeated number of times while traveling the light guide plate 40-A, thereby providing a surface light source to a liquid crystal panel. A reflection plate 20, which is positioned on a rear surface of the light guide plate 40-A, reflects the light having passed the rear surface of the light guide plate 40-A toward the liquid crystal panel, thereby improving brightness of light. However, the edge-type LED configuration is disadvantageous in that local dimming is not enabled, that is, unnecessary lamps cannot be turned off.
By contrast, In a case of a direct-type LED backlight unit, as shown in FIG. 2, a plurality of LEDs 30 are disposed in front of a printed circuit board 10 and a reflection plate 20, so that the LEDs are partially turned on/off, thereby enabling local dimming. In this case, however, the number of LEDs 30 may increase when it is intended to ensure brightness uniformity, making it difficult to effectuate a power consumption reducing effect of local dimming.
To solve the problems, there has been proposed a local dimming enabling module-type LED backlight unit, as shown in FIG. 3.
While the backlight unit shown in FIG. 3 is of an edge type, it is configured such that a plurality of LEDs 30 are disposed at regular intervals in front of a printed circuit board 10 and a reflection plate 20, like a direct-type backlight unit, thereby implementing a local dimming effect while reducing the number of LEDs 30. However, in order to evenly disperse light generated from the LEDs 30 to a lateral side, a light guide plate is required. However, the light guide plate cannot be mounted in front of the printed circuit board.